• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.166-166
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• 2006

The photoluminescence (PL) efficiency of $Ir(ppy)_{3}$:PVK is lower than $Ir(ppy)_{3}$:CBP for the whole range of doping concentration and this low PL efficiency can be a reason of the lower efficiency of PhPLED than PhOLED. The lower efficiency is originated from the large bi-excitonic quenching such as the triplet-triplet annihilation. The PhPLEDs showed very short lifetime. The short lifetime was found to be originated from the instability of the doubly reduced $Ir(ppy)_{3^{-2}}$. The double reduction takes place because of the low electron mobility of PVK and large energy difference of LUMO level between PVK and $Ir(ppy)_{3}$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.9
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• pp.682-685
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• 2013

We have fabricated blue phosphorescent organic light-emitting devices (OLEDs) on a plastic substrate. The solution coated poly (9-vinylcarbazole) (PVK) host doped with Bis (3,5-difluoro-2-(2-pyridyl)phenyl_(2-carboxypyridyl)irdium(III) (FIrPic) guest molecules was used as an hole transporting emission layer. The device structure was ITO/PVK:FIrpic (50 nm, xwt%)/TAZ 50 nm)/LiF (0.5 nm)/Al (100 nm). The concentration of FIrpic molecule was varied from 1 wt% to 10 wt%. The OLED on plastic substrate exhibited maximum current efficiency of 18 cd/A with 5 wt% FIrpic molecules were doped into the PVK layer.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.762-765
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• 2002

The bilayer organic light-emitting diode using Al (DBM) $_3$ (DBM=Dibenzoylmethane) as an emitting material and poly (N-vinylcarbazole) (PVK) as hole-transport material, emitted bright blue-green light instead of blue light. The blue-green emission is attributed to exciplex formation at the solid interface between Al (DBM) $_3$ and the hole-transport material. The exciplex formation was evidenced by the measurement of the photoluminescence spectra and lifetimes of Al (DBM) $_3$, PVK and an equimolar amount of mixture of Al (DBM) $_3$ and PVK.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.736-739
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• 2002

We report on white light emission from a light emitting diode(LED) prepared by blending a red emitting copolymer, m-SiPh PPV-co-MEH PPV, and a blue emitting polyvinylcarbazole (PVK). White light emission was realized when the weight ratio of the m-SiPh PPV-co-MEH PPV : PVK equals to 1 : 30, in which the commission Internationale de L'Eclairage coordinates were x=0.3266 and y=0.3438.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.98-101
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• 2002

The effect of morphology on energy transfer and device performance in phosphorescent dye doped polymer light emitting diodes is reported. We selected two host polymers (PVK and PFHP) which have nearly the same potential for the energy transfer to Ir(ppy)$_3$. The PFHP:Ir(ppy)$_3$ film showed b-micron size aggregation, whereas the PVK:Ir(ppy)$_3$ film showed homogeneous and smooth images. As a result, energy transfer is efficient with high emission efficiency in PVK:Ir(ppy)$_3$ whereas little energy transfer and low quantum efficiency are obtained in PFHP:Ir(ppy)$_3$.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.428-428
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• 2012

ZnO 나노 구조는 화학적으로 안정하고 큰 엑시톤 에너지를 가지는 성질 때문에 청색 영역에서 작동하는 광전소자의 제작에 대단히 유용하다. ZnO 나노 구조중에서 ZnO 나노 입자는 UV 광탐지기 소자가 작동하는 영역에서 광반응이 매우 민감하여 연구가 많이 진행되고 있다[1]. 그래핀은 높은 전도도, 투명도 및 화학적, 열적 안정성이 뛰어난 독특한 물리적 특성을 가지고 있기 때문에 차세대 전자소자와 광전소자의 우수한 소재로 각광 받고 있다[2,3]. 본 연구에서는 UV 광탐지기에서 뛰어난 특성을 보이는 ZnO 양자점을 포함된 poly-N-vinylcarbazole (PVK) 층에 전기적 특성이 뛰어난 그래핀 층을 삽입하여 UV 광탐지기의 광전류를 향상 시키는 연구를 하였다. PVK 표면에 ZnO 양자점이 붙어서 형성되어 있는 모습과 그래핀 층에 PVK와 ZnO QD가 붙어있는 것을 투사 전자 현미경을 통하여 관찰 하였다. 전류-접압 측정을 하여 암전류와 광전류의 차이가 많이 나는 것을 알 수 있었다. 그래핀 층을 삽입한 광탐지기 소자에서 광전류가 향상되는 것을 알 수 있었다.

• 한국정보디스플레이학회:학술대회논문집
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• 2000.01a
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• pp.127-128
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• 2000

Organic light-emitting diodes(OLEDs) are constructed using multilayer organic thin films. The hole-transport layer is PVK and the emitting material is rubrene and $Alq_3$. The emitting layer is doped with rubrene partially. As the partially-doped layer migrate from the interface PVK/emitting layer, the emission peak of rubrene decrease and diminish. By comparing with the previous reports, we propose the zero-field hole injection barrier at ITO/PVK interface and hole-trapping effect of rubrene in host materials as predominant factor to determine the emission zone.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.5
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• pp.376-382
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• 2000

We successfully fabricated OLED(Organic Light Emitting Diodes) with Al cathodes electrode deposited by the DC magnetron sputtering. The effects of a controlled Al cathode layer of an Indium Tin Oxide (ITO)/blended single polymer layer (PVK Bu:PBD:dye)/Al light emitting diodes are described. The PVK (Poly(N-vinylcarbazole)) and Bu-PBD (2-(4-biphenyl-phenyl)-1,3,4-oxadiazole) are used hole transport polymer and electron transport molecule respectively. We found that both current injection and electroluminescence output are significantly different with a variable DC sputtering power. The difference is believed to be due to the influence near the blended polymer layer/cathode interface that results from the DC power and H$\sub$2//O in a chamber. And DC sputtering deposition is an effective way to fabricate Al electrodes with pronounced orientational characteristics without damage occurring to metal-organic interface during the sputtering deposition.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2006.04a
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• pp.82-83
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• 2006

• Proceedings of the Optical Society of Korea Conference
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• 2001.02a
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• pp.206-207
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• 2001

The photorefractive (PR) effect in liquid crystals sandwiched between photoconductive polymer layers was first studied by Ono et al. They reported that the PR effect vanished at steady state If there were not insulating layers because no charge trapping occurred in the photoconductive poly(N-vinylcarbazole) (PVK) layers. However we observed a significant PR effect in the polymer layered liquid crystal (PLLC) system where a liquid crystal layer doped with fullerene is sandwiched between two photoconductive PVK layers. (omitted)